1. Field of the Invention
The present invention relates to photography and more particularly to bellows for folding type cameras.
2. Description of the Prior Art
Cameras having large film formats normally require a taking lens having a correspondingly long focal length. It is convenient if such cameras can be folded while not in use so as to occupy a minimum of storage space. It has long been known that bellows coupling the camera body and a lens assembly of such folding cameras provide a practical means for achieving a light-tight enclosure between the lens and the camera body.
In one known type of folding camera, the lens is supported at one end of a cover door that is hinged to the camera housing at its opposite end. A collapsible folding bellows allows the lens to be extended by opening the door to an oblique angle relative to the camera housing. In keeping the overall dimensions of the folded camera to a minimum, a major consideration has been the thickness and location within the camera of the folded bellows.
One approach has been to locate the folded bellows between the film plane and the cover door when the cover door is closed. To keep the overall thickness of the camera to a minimum, it is known to provide the bellows with just a single pleat. This arrangement is shown in U.S. Pat. No. 2,880,658. U.S. Pat. No. 1,851,095 shows a two-part bellows. The main part of the bellows has one pleat and folds flat between the cover door and the film plane. The second bellows part connects the main part of the bellows to the lens housing to enable the lens housing to be folded into the same plane as the cover door when the cover door is closed. In this arrangement, when the cover door is open and the lens housing is in a picture taking position, the second bellows part is collapsed.
Although the single pleated bellows take up a minimum of space when folded, they are very unstable and the lateral portions which pivot inwards are subjected to considerable strain in the regions where the pleat edges join, with the result that the bellows are subject to failure in these areas.
Bellows having several or many accordion-like pleats are more stable and tend to be more durable because they are subjected to less strain when folded. However, because of their construction they can be folded no thinner than the combined thickness of all the pleats. A camera of the type having a multi-pleated accordion-like bellows is shown in U.S. Pat. No. 2,906,182. In this camera, the front cover door has been hollowed out to receive the folded bellows with a consequent increase in the overall thickness of the camera. To minimize the overall thickness of the camera, it is known to employ a U-shaped accordion-pleated bellows that is stored, when the camera is closed, around three sides of a film pack. Such a camera is shown in U.S. Pat. No. 3,677,160. Since the U-shaped bellows surrounds the film pack on three sides, the overall thickness of the camera is minimized, but the width and length of the camera are increased by an amount sufficient to accommodate the folded bellows around the film pack.
Bellows of the kind which have multiple pleats for minimum strain and which fold flat between the camera cover and the film plane are known for use with a folding camera of the type in which the optical path is deflected to the negative material by a mirror. An example of this type of bellows is shown in U.S. Pat. No. 3,678,831. However, the deflection of the optical path results in a smaller pivot angle between the camera housing and the cover door and consequently a smaller bellows. Thus the smaller bellows can be folded relatively flat in a minimum of space. Such a bellows as described above is not, however, suitable for folding cameras which do not have optical path deflection, since in that case a larger pivot angle between the camera body and the cover is necessary. The number of pleats must be increased to produce a low-strain bellows in a camera without optical path deflection. Such a bellows would be thicker when folded, thus increasing the overall-thickness of the camera.